For in the home consumer video applications (TV) quality of service is critical, image breakup, stalling or other artifacts are not acceptable for the market/customer. This presents a serious problem for network based distribution of video in the home, in that the available bandwidth in these networks tends to be unstable/unpredictable. Changing available bandwidth can cause the client devices to fall behind and eventually run out of data for display resulting in the aforementioned issues. Wireless and home-plug based networks are particularly sensitive to this issue because of interference from other devices inside (and outside) the home. However, even if Ethernet or Fiber is available (very rare) changes in network demand based on user usage can cause the same issues. For instance transferring large files or printing while simultaneously streaming video often creates a network bottleneck which the video cannot recover from without visible artifacts.
Most current approaches use a constant bit rate (or near constant) for network video transmission, which requires the smallest available bandwidth to be known prior to initiating the video stream. Since bit rate (bandwidth) and image quality are highly correlated with higher bit rates resulting in better quality, selecting the lowest possible bandwidth will result in the lowest image quality. Even in the case where variable bit rate technology is used it must maintain over the long term a rate that matches the worst case network conditions using today's technology.
The need remains therefore for a way to dynamically adapt to the available network bandwidth so as to optimize image quality.